The polyphenylene oxides and methods for their preparation are known in the art and are described in numerous publications, including Hay, U.S. Pat. Nos. 3,306,874 and 3,306,875. The Hay processes are based on the use of copper-amine complexes as catalysts for the oxidative coupling of phenolic monomers. Manganese catalyzed methods for the preparation of polyphenylene oxides are disclosed in McNelis, U.S. Pat. Nos. 3,220,979; Olander, 3,956,242; Nakashio, 3,573,257; and Nakashio, 3,787,361. Cizek, U.S. Pat. No. 3,383,435, discloses compositions of polyphenylene oxides and styrene resins which are useful thermoplastic molding compositions.
In the applicant's copending applications Ser. No. 491,370, filed July 24, 1974 and Ser. No. 534,903 filed Dec. 20, 1974, there are disclosed novel procedures for polymerizing polyphenylene oxides with complex manganese based catalysts. All of these patents and applications are hereby incorporated by reference.
The processes which have used manganese based catalysts have employed both chelated manganese and manganese salts without any chelate forming compound. In U.S. Pat. No. 3,573,257, a process is disclosed that is characterized by the use of a managnese salt with an alkali alcoholate in the absence of an amine. This patent denigrates the use of amines and actually states that amines should now be used since amines tend to cause deterioration of the properties of the polymer.
It has been discovered that the process disclosed in U.S. Pat. No. 3,573,257 can be improved if a secondary amine is employed in conjunction with a manganese salt and a basic reaction media. The improvements that result from the use of a secondary amine in conjunction with a manganese salt for the oxidative coupling of phenolic monomers, include a more controlled process that permits the selection of a termination point and which yields a polymer having improved properties as compared to a polymer made in the absence of a secondary amine.
Accordingly, it is a primary object of this invention to provide an improved process for the production of polyphenylene oxides by means of a catalyst which comprises a manganese salt and a secondary amine.
It is a further object of this invention to provide a process for the preparation of a polyphenylene oxide with a manganese salt that provides a polyphenylene oxide having improved properties as compared to a polyphenylene oxide that is prepared with other manganese catalyst systems .